: Mammary gland is a compound alveolar gland that secretes milk which has nutritive and immunologic functions. In the human female, they are made up of lobes and lobules bound together by areolar tissue. The main ducts are 15 to 20 in number and are known as lactiferous ducts, each one discharging through a separate orifice on the surface of the nipple. The dilations of the duct form reservoirs for the milk during lactation. The pink or dark-coloured skin around the nipple is called the areola.